Random problems when receiving messages

Q: I have a problem with the receiving of sms with a Siemens MC45 modem and the Boomerang comps.

I try it with the TC35 settings at 19200 baud.

When i send 15 messages and try to query the modem all 2 seconds (what works with tc35) I get at the second message the error AT+CMGD=1 that the second message cannot bedeleted ? No answer to the command. The result is that i receive some twice and some not.

What i think is that maybe something is too slow.

Do you have expirience with that what do you think does work wrong.

A: It's dependent on modem firmware how robustly is written, e.g. TC35 is good, M20 is tragic. The problem probably is that on one line are mixed two signal flows. If you have unsolicited indication - modem can send its command anytime and if in the same time get command from machine may switch to strange state.

Maybe you can switch off unsolicited messages and poll messages using GetSMSList instead (to avoid async communication from modem) or try upgrade firmware if possible.